This tutorial will demonstrate the process of decoking the top end, or removing the carbon deposits from the engine. This is a standard maintenance and should be performed every 6000km (4000 miles), or every year for machines that are never heating up (quick hops about town). It will be virtually impossible to get all the crud off of the engine parts, so don't be overly compulsive about it. Though the process seems daunting, like putting a wheel together, it is one of those chores that you will be able to fly through after your first go. I would give it a few hours for the first time. I hear some asking, "why should I do this; my engine runs fine?" This procedure is important because of the heat and power restrictions a two stroke engine has to contend with. By letting junk build up on the piston, cylinder and head, you are effectively decreasing the fuel capacity of your motor (ie 200 cc to something slightly less). Since waste carbon, commonly called coke, is left from burning two stroke oil, the engine will suffer from an overly "rich" condition and generally run badly or start hard. A few signs that your top-end may need to be cleaned are oily, constantly fouling spark plugs; hard starting (more than 4 kicks) and lots of exhaust smoke. I would reccomend you preced this operation with a carb rebuild when attempting for the first time. Synthetic lubricants will increase the period of this procedure, but it is still worthwhile to consider attempting every year. This procedure is best done in a covered, well lit area (like a garage) so no crap gets into your top end.